Epoxy-modified encapsulation composition

ABSTRACT

Epoxy-grafted, low molecular weight amorphous polymer compositions are employed in pourable, liquid telecommunication cable encapsulation compositions. Also disclosed is a method for encapsulating telecommunication cables as well as cables encapsulated with such an epoxy-grafted liquid encapsulant.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of application Ser. No. 07/058,000filed Jun. 4, 1987, now U.S. Pat. No. 4,787,703, which in turn is acontinuation-in-part of application Ser. No. 06/787,870 filed Oct. 16,1985, now abandoned.

FIELD OF THE INVENTION

This invention is directed to a pourable liquid encapsulationcomposition for telecommunication cables which is comprised of (a) anamorphous low molecular weight epoxy-grafted polymer having a backboneselected from the group consisting of polyalphaolefin,ethylene/alphaolefin copolymer, ethylene/alphaolefin/non-conjugatedpolyene terpolymer, polyisoprene, polybutadiene and alphaolefin/polyenecopolymer; and (b) a curative therefore. In other aspects, thisinvention is directed to novel graft polymers which may be employed inthe composition of this invention; to a method of encapsulatingtelecommunication cables employing such encapsulation composition; andto a telecommunication cable encapsulated with such encapsulantcomposition.

BACKGROUND OF THE INVENTION

Telecommunication cables, whether of the metallic or fiber opticvariety, are frequently employed in situations wherein water can enterand migrate through the cable system. Water entry into either copper orfiber optic cables is undesirable because it leads to deterioration oftransmission properties due to corrosion, particularly at the siteswhere cables are spliced together. In order to protect the cable system,it has become known to encase certain segments of the cable in a closurewhich acts as an extension of the cable sheath or cover. In addition, ithas become known to encapsulate the enclosed segment with a curableencapsulant so as to prevent water migration into the segment.

Examples of cable segments which are typically placed in closures andencapsulated are the area where two or more cables are spliced together(i.e., a splice), the end of the cable (i.e., an end block), and thejunction between an air pressurized cable and a hydrocarbon greasefilled cable (i.e., pressure block).

In addition to preventing water migration into the telecommunicationcable splice, it is often desirable for the encapsulant to bere-enterable. Re-enterable means that upon opening a closure containinga cured encapsulant, the encapsulant can be entirely removed from thesplice area by hand (using no tools in the area around the copper wiresor fiber optic filaments) without damaging the individual wire orfilament connections and without removing any of the insulation on thecopper wires or any of the coating on the fiber optic filaments. Sincethe splice closure is encapsulated at on-site locations in the fieldwhere the cable is being layed, the encapsulant must also be capable ofbeing poured as well as cured over a wide range of ambient temperatures(35°-100° F.).

Among the materials exhibiting insulation and thermal resistanceproperties which are desirable for encapsulation purposes areterpolymers of ethylene, propylene and a nonconjugated diene (i.e.,"EPDM"). Thus, U.S. Pat. No. 3,974,132 to Valdiserri discloses theinsulation and coating of electrically conducting wire with EPDM whichis crosslinked with a trialkyl phosphate. However, several disadvantagesare associated with the use of EPDM polymers such as those disclosed inthis patent.

Primary among these disadvantages is that the EPDM employed in theValdiserri and other similar processes is a high molecular weightmaterial which must be pelletized. Consequently, in order to adapt theembedding composition to the configuration of the circuitry to beprotected, such pelletized EPDM must be simultaneously subjected to heatand pressure. Such pressure and temperature requirements prohibit theaccomplishment of on-site encapsulation of telecommunication cables,e.g., for the protection of splices or other on-site repairs.

U.S. Pat. No. 3,448,174, issued to Loveless, shows low molecular weightepoxy-modified ethylene/propylene/dicyclopentadiene terpolymers whereinthe pendent dicyclopentadiene group itself is epoxy modified, anddiscloses that such compounds are useful as casting and coatingcompositions.

Tachi et al, in U.S. Pat. No. 4,245,061, disclose epoxy-modified waxeshaving a number average molecular weight of between 600 and 10,000. Suchwaxes are blended with a thermosetting resin to form compositions whichare useful as paints, adhesives or molding materials.

U.S. Pat. No. 4,388,202, issued to Nagano et al, discloses lubricatingoil compositions which comprise uncured epoxy-grafted polymers havingsaturated backbones and number average molecular weights ranging fromabout 5,000 to about 100,000.

However, none of the above-discussed patents disclose an encapsulationcomposition for telecommunication cables which may be readily appliedand cured at or near ambient temperatures and pressures, which would notendanger the wires or filaments to be protected and which is amenable toon-site application to protect splices and the like.

Accordingly, it is an object of this invention to provide a pourableliquid encapsulation composition which may be cured at ambient orslightly elevated temperatures and pressures, and which may therefore beemployed to protect metallic and/or fiber optic telecommunicationcables.

It is further object of this invention to provide an encapsulationcomposition which may be employed for on-site applications.

It is yet another object of this invention to provide a method ofencapsulating telecommunications cables employing such composition.

It is yet another object of this invention to provide an epoxy-graftedpolymer which may be employed in the composition of this invention.

It is yet a further object of this invention to provide atelecommunications cable segment encapsulated with such an encapsulantcomposition.

The above objects and additional objects will become more fully apparentfrom the following description and accompanying Examples.

DESCRIPTION OF THE INVENTION

In one aspect, this invention relates to a pourable, liquid compositioncomprising:

(A) a liquid graft polymer having a Brookfield viscosity of less thanabout 1,000,000 centipoise at 25° C., which graft polymer eitherpossesses no melting transition peak or possesses a melting transitionpeak having a maximum value below 25° C. as measured by DifferentialScanning Calorimetry;

said graft polymer being comprised of: a polymeric backbone selectedfrom the group consisting of polyalphaolefin, ethylene/alphaolefincopolymer, ethylene/alphaolefin/nonconjugated polyene terpolymer,polyisoprene, polybutadiene, and alphaolefin/polyene copolymer;

said polymeric backbone having grafted thereto a sufficient amount of atleast one compound selected from the formulae: ##STR1## wherein R" is aC₂ -C₁₆ hydrocarbon radical containing an ethylenically unsaturated bondor a C₃ -C₁₂ radical containing one or more carbonyl groups and anethylenically unsaturated double bond; and R' is hydrogen or C₁ -C₄alkyl;

such that said graft polymer is rendered crosslinkable;

said graft polymer having a number average molecular weight of betweenabout 500 and about 20,000; and

(B) a sufficient amount of a suitable curative to cure the composition.

In another aspect, this invention is directed to:

(A) a liquid graft polymer having a Brookfield viscosity of less thanabout 1,000,000 centipoise at 25° C., said graft polymer eitherpossessing no melting transition peak or possessing a melting transitionpeak having a maximum value below 25° C. as measured by DifferentialScanning Calorimetry;

said graft polymer being comprised of: a polymeric backbone selectedfrom the group consisting of polyalphaolefin, ethylene/alphaolefincopolymer, ethylene/alphaolefin/nonconjugated polyene terpolymer,polyisoprene, polybutadiene, and alphaolefin/polyene copolymer;

said polymeric backbone having grafted thereto a sufficient amount of atleast one compound selected from the formulae: ##STR2## wherein R" is aC₂ -C₁₆ hydrocarbon radical containing an ethylenically unsaturated bondor a C₃ -C₁₂ radical containing one or more carbonyl groups and anethylenically unsaturated double bond; and

R' is hydrogen or C₁ -C₄ alkyl;

such that said graft polymer is rendered crosslinkable; said graftpolymer having a number average molecular weight of between about 500and about 4,500.

In yet another aspect, this invention relates to a method ofencapsulating a telecommunication cable segment comprising the steps:

(A) placing a telecommunications cable segment within a closure;

(B) forming an encapsulation composition by mixing:

(1) a liquid graft polymer having a Brookfield viscosity of less thanabout 1,000,000 centipoise at 25° C.; said graft copolymer eitherpossessing no melting transition peak or possessing a melting transitionpeak having a maximum value below 25° C. as measured by DifferentialScanning Calorimetry;

said graft polymer being comprised of: a polymeric backbone selectedfrom the group consisting of polyalphaolefin, ethylene/alphaolefincopolymer, ethylene/alphaolefin/nonconjugated polyene terpolymer,polyisoprene, polybutadiene, and alphaolefin/polyene copolymers;

said polymeric backbone having grafted thereto a sufficient amount of atleast one compound selected from the formulae: ##STR3## wherein R" is aC₂ -C₁₆ hydrocarbon radical containing an ethylenically unsaturated bondor a C₃ -C₁₂ radical containing one or more carbonyl groups and anethylenically unsaturated double bond; and

R' is hydrogen or C₁ -C₄ alkyl;

such that said graft polymer is rendered crosslinkable; said graftpolymer having a number average molecular weight of between about 500and about 20,000; with

(2) a sufficient amount of a suitable curative to cure the composition;

(C) pouring a sufficient amount of said encapsulation composition intothe closure such that the portion of said telecommunication cablesegment to be embedded is covered with said encapsulation composition;and

(D) subjecting said encapsulation composition to curing conditions.

In yet another aspect, this invention relates to a telecommunicationcable segment having at least a portion thereof coated with a pourableliquid composition comprising:

(A) a liquid graft-polymer having a Brookfield viscosity of less thanabout 1,000,000 centipoise at 25° C., said graft polymer eitherpossessing no melting transition peak or possessing a melting transitionpeak having a maximum value of below 25° C. as measured by DifferentialScanning Calorimetry;

said graft polymer being comprised of: a polymeric backbone selectedfrom the group consisting of polyalphaolefin, ethylene/alphaolefincopolymer, ethylene/alphaolefin/nonconjugated polyene terpolymer,polyisoprene, polybutadiene, and alphaolefin/polyene copolymer;

said polymeric backbone having grafted thereto a sufficient amount of atleast one compound selected from the formulae: ##STR4## wherein R" is aC₂ -C₁₆ hydrocarbon radical containing an ethylenically unsaturated bondor a C₃ -C₁₂ radical containing one or more carbonyl groups and anethylenically unsaturated double bond; and

R' is hydrogen or C₁ -C₄ alkyl; such that said graft polymer is renderedcross-linkable;

said graft polymer having a number average molecular weight of betweenabout 500 and about 20,000; and

(B) a sufficient amount of a suitable curative to cure the composition.

The encapsulation composition of this invention is comprised of (1) agraft polymer and (2) a curative. Such graft polymers comprise apolymeric backbone having an epoxy-functional compound grafted thereto.

The polymeric backbone of the graft polymer of the composition of thisinvention is selected from the group consisting of polyalphaolefin,ethylene/alphaolefin copolymer, ethylene/alphaolefin/nonconjugatedpolyene terpolymer, polyisoprene, polybutadiene, and alphaolefin/polyenecopolymer. Preferably, such backbone is composed of a polyalphaolefin,ethylene/alphaolefin copolymer or ethylene/alphaolefin/nonconjugatedpolyene terpolymer. Particularly preferred backbones includeethylene/propylene copolymer, and ethylene/propylene/non-conjugateddiene terpolymer (EPDM).

The polyalphaolefin, polyisoprene and polybutadiene polymers that may beemployed may be homopolymers of these monomers or copolymersadditionally comprising a minor amount of another monomer or monomersexhibiting vinyl unsaturation such as styrene, acrylate, methacrylate,acrylonitrile, methacrylonitrile and the like, provided that thepresence of such other monomers does not detrimentally affect thecharacteristics of the grafted polymers. Moreover, the polyisoprene andpolybutadiene polymers may be unhydrogenated, partially hydrogenated orfully hydrogenated.

The polyalphaolefin polymers that may form the backbone of the graftpolymers of this invention are homo- or copolymers of one or morealphaolefins having the formula H₂ C═CHR wherein R is a linear orbranched alkyl radial containing from 1 to 10 carbon atoms. Preferably,R is C₁ -C₈ alkyl. The most preferred alphaolefins are propylene,1-butene, 1-hexene and 1-decene.

The ethylene/alphaolefin copolymers which may be employed in thepractice of this invention are copolymers of ethylene and at least onealphaolefin having the formula H₂ C═CHR wherein R is a linear orbranched alkyl radial containing from 1 to 10 carbon atoms. Preferably,R is C₁ -C₈ alkyl. The most preferred alphaolefins are propylene,1-butene and 1-hexene.

The ethylene/alphaolefin/nonconjugated polyene terpolymers which may beemployed are polymers of ethylene, at least one alphaolefin (of theformula H₂ C═CHR, wherein R is a linear or branched alkyl radicalcomprised of from 1 to 10 carbon atoms) and at least one copolymerizablenonconjugated polyene. Illustrative of the nonconjugated polyenes whichmay be employed are aliphatic dienes such as 1,4-hexadiene,1,5-hexadiene, 1,4-pentadiene, 2-methyl-1,4-pentadiene,3-methyl-1,4-hexadiene, 4-methyl-1,4-hexadiene, 1,7-octadiene,1,9-decadiene, exo-and endo- dicyclopentadiene and the like; exo- andendo- alkenylnorbornenes, such as 5-propenyl-, 5-(buten-2-yl)-, and5-(2-methylbuten-[2']-yl)norbornene and the like;alkylalkenylnorbornenes, such as 5-methyl-6-propenylnorbornene and thelike; alkylideneorbornenes, such as 5-methylene-, 5-ethylidene-, and5-isopropylidene-2-norbornene, vinylnorbornene, cyclohexenylnorborneneand the like; alkylnorbornadienes, such as methyl-, ethyl-, andpropylnorbornadiene and the like; and cyclodienes such as1,5-cyclooctadiene, 1,4-cyclooctadiene and the like. The preferrednonconjugated polyenes are 5-ethylidene-2-norbornene, 1,4-hexadiene anddicyclopentadiene.

The ethylene content of the ethylene/alphaolefin copolymers andethylene/alphaolefin/nonconjugated polyene terpolymers that may beemployed is generally between about 25% and about 85%, is preferablybetween about 30% and about 75%, and is most preferably between about40% and about 70%, all by weight. The polyene content of suchterpolymers is generally below about 25%, and is preferably betweenabout 2 and about 20%, all by weight.

The alphaolefin/polyene copolymers which may form the backbone of thepolymers employed in the encapsulation composition of this invention arecopolymers of at least one alphaolefin having the formula H₂ C═CHR,wherein R is a linear or branched alkyl radial containing from 1 to 10carbon atoms, and at least one conjugated or nonconjugated polyene.

Particularly preferred polymer backbones for the graft polymers employedin the composition of this invention are low molecular weight copolymersof ethylene, an alphaolefin and (optionally) a nonconjugated polyene,which copolymers have a viscosity index of at least about 75 andvinylidene-type unsaturation. These copolymers are described in U.S.Pat. No. 4,668,834 and are readily prepared employing metallocenecatalysts such as (C₅ H₅)₂ Zr(CH₃)₂, (C₅ H₅)₂ Ti(CH₃)₂, (C₅ H₅)₂ ZrCl₂,(C₅ H₅)₂ TiCl₂ and the like, in combination with linear or cyclicaluminoxane cocatalysts, such as methaluminoxane.

The polymeric backbones have grafted thereto a sufficient amount of acompound having epoxy functionality such that such graft polymers arerendered crosslinkable and such that the said graft polymers areessentially amorphous liquids at room temperature. As employed in theinstant specification, an amorphous liquid polymer is defined as apolymer (1) having a Brookfield viscosity of less than about 1,000,000centipoise at 25° C.; and (2) either having no crystalline melting pointor a crystalline melting point with a maximum value below 25° C. asmeasured by Differential Scanning Calorimetry. In general, such epoxygroups will comprise between about 1 and about 20, preferably betweenabout 1 and about 12, more preferably between about 1.5 and about 10,and most preferably between about 2.5 and about 7 weight percent of thegraft polymer. Preferably, the epoxy functionality is present in amountsof between about 1 and about 10 groups per polymer chain. Morepreferably between about 1.5 and about 6, and most preferably betweenabout 2 and about 4.5 epoxy groups per polymer chain are present.

The epoxy-functional compounds which may be grafted to the polymericbackbone are of the formulae: ##STR5## wherein R" is a C₂ -C₁₆hydrocarbon radical containing an ethylenically unsaturated bond or a C₃-C₁₂ radical containing one or more carbonyl groups and an ethylenicallyunsaturated double bond; and R' is hydrogen or C₁ -C₄ alkyl. Preferably,R is a C₂ -C₁₂ hydrocarbon group containing an ethylenically unsaturatedbond or is an acrylate or a methacrylate group.

Illustrative of the epoxy functionalized compounds which may be employedare allyl glycidyl ether, 2-methylallyl glycidyl ether, o-allylphenylglycidyl ether, m-allylphenyl glycidyl ether, p-allylphenyl glycidylether, isopropenylphenyl glycidyl ether, o-vinylphenyl glycidyl ether,m-vinylphenyl glycidyl ether and p-vinylphenyl glycidyl ether;2-(o-vinylphenyl)ethylene oxide, 2-(o-vinylphenyl)propylene oxide,2-(p-vinylphenyl)propylene oxide, 2-(o-allylphenyl)ethylene oxide,2-(o-allylphenyl)propylene oxide, 2-(p-allylphenyl)propylene oxide,p-glycidylstyrene, 3,4-epoxy-1-butene, 3,4-epoxy-3-methyl-1-butene,3,4-epoxy-1-pentene, 3,4-epoxy-3-methyl-1-pentene, 5,6-epoxy-hexene,1,2-epoxy-7-octene, vinylcyclohexene monoxide andallyl-2,3-epoxycyclopentyl ether, glycidyl acrylate, and glycidylmethacrylate. Preferred epoxy compounds are allyl glycidyl ether,2-methallyl glycidyl ether, isopropenylphenyl glycidyl ether,allylphenyl glycidyl ether and 2-(allylphenyl)ethylene oxide.

The graft polymers which may be employed generally possess a numberaverage molecular weight of between about 500 and about 20,000,preferably of between about 750 and about 10,000, and most preferably ofbetween about 1,000 and about 4,500. Such graft copolymers are novelcompounds when they possess a number average molecular weight of belowabout 4,500.

Moreover, the graft polymers employed in this invention possess a glasstransition temperature of less than about 25° C., preferably of lessthan about -20° C., most preferably of less than about -35° C. Suchgraft polymers are essentially amorphous liquids that are readilypourable at room or slightly elevated temperature, having a Brookfieldviscosity of less than about 1,000,000 centipoise, preferably of lessthan about 500,000 centipoise, at 25° C. The graft-polymers of thisinvention are essentially amorphous in that they do not possess amelting transition peak or possess a melting transition peak with amaximum value below 25° C., preferably of below 20° C. and mostpreferably of below 10° C., as measured by Differential ScanningCalorimetry.

The graft polymers employed in the practice of this invention may beprepared by contacting the polymeric backbone with an epoxy-functionalcompound at between about 50° and about 200° C., in the presence of afree radical generator such as organic hydroperoxides or peroxides, oran azonitrile. The free radical generator is generally employed inamounts between about 0.05 and about 30, preferably between about 0.4and about 30 percent by weight, based upon the weight of the polymericmaterial.

Free radical generators which may be employed in carrying out the graftreaction include aromatic or aliphatic (hydro)peroxides, includingaromatic diacyl peroxides and aliphatic diacyl peroxides, diabasic acidperoxides, ketone peroxides, alkyl peroxyesters and alkylhydroperoxides. Illustrative of the (hydro)peroxides which may beemployed are diacetylperoxide, dibenzoylperoxide,bis-2,4-dichlorobenzoyl peroxide, ditert-butyl peroxide,dicumylperoxide, tert.-butylperbenzoate, tert.-butylcumyl peroxide,2,5-bis(tert.-butylperoxy)2,5-dimethylhexane,2,5-bis-(tert.-butylperoxy-2,5-dimethylhexyne-3,4,4,4',4'-tetra-(tert.-butylperoxyl)-2,2dicycloxylpropane,1,4-bis-(tert.-butyl-peroxy-isopropyl)-benzene,1,1-bis-(tert.-butylperoxy)-3,3,5-trimethylcyclohexane, lauroylperoxide, succinic acid peroxide, cyclohexanone peroxide, tert.-butylperacetate, butyl hydroperoxide, and the like.

Free radical generators which are also suitable include azide-typecompounds such as azidoformates, for exampletetramethylenebis(azidoformate) and the like; aromatic polyazides suchas 4,4'-diphenylmethane diazide and the like; and sulfonazides such asp,p'-oxybis (benzenesulfonyl azide) and the like. Particularly preferredfree radical generators include di-t-butyl peroxide and dicumylperoxide.

The curative employed in the composition of this invention may compriseany compound which cure epoxy groups. Preferably, such curative will beeffective at ambient temperatures. Illustrative of curatives which maybe employed are linear aliphatic polyamines such as diethylene triamine,triethylene tetramine, tetraethylene pentamine, dipropylenediamine anddiethylaminopropylamine and the like; cyclic aliphatic polyamines;aliphatic polyamine adducts; ketimines; modified aliphatic amines;aromatic amines; aromatic modified amines; tertiary amine-type curingagents; mercapto-type curing agents; acid anhydride-type curing agents;Lewis Acid type curing agents such as BF₃ and SnCl₄ complexes;copolymers containing an acid anhydride group such as ethylene/maleicanhydride copolymers; compounds containing a phenolic hydroxyl groupsuch as precondensates of phenolic resins; and other curing compoundssuch as dicyandiamide and melamine.

The amount of curative which may be employed will vary in accordancewith a number of factors, including the particular curative selected,the degree of epoxidation present of the graft polymers, the degree ofcure desired, and the like. However, one skilled in the art may beroutine experimentation determine the optimum levels of curative for agiven encapsulation composition.

The compositions of this invention may further comprise cureaccelerators in order to decrease their gelling or setting time. Any ofthe known epoxy-cure accelerators may be employed, provided that theprotection afforded by the encapsulant is not adversely affected.Preferred accelerators include alkylphenols such as nonylphenol,dodecylphenol, and the like. The preferred amounts of accelerators willdepend on a variety of factors, including the curative employed, theamount of epoxy-functionality present, the amount of curative employed,and the like. However, one of ordinary skill in the art may readilydetermine the optimum amount of accelerator to be employed in a givenencapsulation composition by routine experimentation.

Moreover, the encapsulation compositions of this invention mayadditionally comprise (preferably minor) amounts of diluents in order toincrease their pourability. Such diluents may be reactive ornonreactive. Particularly preferred diluents include alkyl glycidylethers, which will react with the curative and which, consequentially,cannot be leached out as well as other epxoy-functionalized reactivecompounds which will increase the pourability of the composition.

The telecommunication cable segments which may be encapsulated with theencapsulation composition of this invention may be of the metallic or ofthe fiber optic type. Because of its pourability and curability atambient or slightly raised temperature, the compositions of thisinvention are admirably suited for the on-site encapsulation of cablesegments such as splices, pressure blocks and end blocks.

The method of this invention is typically performed as follows. Atelecommunication cable segment is placed within a closure. Such closureserves to act (in part) as a retainer for the liquid encapsulationcomposition. Accordingly, said closure may generally be of any usefulconfiguration or composed of any useful material, although in certaininstances a particular configuration and/or material may be preferred.The liquid encapsulation composition of this invention is typically thenprepared by mixing the graft polymer with the curative. Said mixing maybe accomplished by any means effective to adequately disperse thecurative within the graft polymer such that curing will occur.

The mixted encapsulation composition is poured into the closure suchthat said composition covers at least that portion of the cable segmentto be protected. Such pouring is preferably accomplished at ambienttemperatures, although slightly elevated temperatures (typically up toabout 65° C.) may be employed. It is to be understood that such pouringmay be accomplished at any temperature below the decompositiontemperature of the encapsulation composition which will not cause damageto the cable segment to be protected.

The encapsulation composition is then subjected to curing conditions. Inthe preferred embodiments of this invention, curing conditions generallycomprise ambient temperature and pressure.

The encapsulation compositions of this invention are easily adaptablefor on-site repairs due to their ease of application and exhibitexcellent adhesion to wire. Moreover, because these compositions will,in general, cure at ambient temperatures and pressures, thetelecommunication cable to be protected is not subjected to thermal orpressure shocks while being encapsulated. Telecommunication cablesegments protected by the encapsulation composition of this inventionwill be less vulnerable to damage resulting from water entry.

Compared with the polyurethane gels based on hydroxy terminatedpolybutadiene currently used to encapsulate splices in thetelecommunication industry, the encapsulation compositions of thisinvention generally provide better moisture resistance due to the higherhydrolytic stability of epoxide crosslinks vis-a-vis urethane linkages;improved compatibility with hydrocarbon based compounds used to filltelecommunication cables; and improved adhesion to polyethyleneinsulated conductor wires which are coated with the cable fillingcompound.

These advantages act together to increase the durability and to reducethe maintenance costs of telecommunication cable splices, particularlythose splices which are buried underground. Urethane encapsulants' poorcompatibility with cable filler and poor conductor wire adhesion allowswater which enters the cable system to travel through the splice to thewire contacts where corrosion may cause a splice failure. The improvedcompatibility with cable filler and improved conductor wire adhesion ofthe encapsulant compositions of this invention will prevent or greatlyreduce the frequency of such warer corrosion related failures caused bysuch water entry.

EXAMPLES

The following Examples are intended to further illustrate the inventionare not intended to limit the scope of the invention in any mannerwhatsoever.

EXAMPLES 1-9

To a dry 3-liter glass resin flask equipped with a mechanical stirrer,thermometer, distilling head, heating mantle and nitrogen inlet tubewere added 935 grams liquid ethylene-propylene copolymer (having anumber average molecular weight of 2,200 and an ethylene/propylene (E/P)molar ratio of 60:40) and a mixture of 50.6 grams di-t-butyl peroxide in234 grams of allyl glycidyl ether at room temperature. The reactor wasflushed with dry nitrogen during such addition. The nitrogen was shutoff and the reactor heated to 150° C. during which time the reactionmixture was stirred. As the reaction was proceeding, acetone andt-butanol (the decomposition products of the peroxide) were removed bydistillation. The reaction was carried out for 4 hours after which timethe reaction mixture was vacuum stripped at 150° C. and at about 260 Papressure for one hour. The modified polymer product was then removedfrom the reactor. The results of an analysis of the graft polymer soprepared is listed in Table I below as Example 1.

Following a similiar procedure to that described in Example 1, severaladditional epoxy-grafted ethylene/propylene copolymers (Examples 2-9)were prepared. The backbone polymers, graft initiators and the resultsof analyses performed on the resultant graft copolymers are summarizedin Table 1.

                                      TABLE I                                     __________________________________________________________________________    Epoxy-Grafted Ethylene/Propylene Copolymers                                   EXAMPLE    1    2    3    4    5     6    7    8    9                         __________________________________________________________________________    Backbone Polymer                                                              Catalyst   Zr.sup.(1)                                                                         Zr   V.sup.(2)                                                                          V    Zr    Zr   V    Zr   V                         Ethylene/Propylene                                                                       60/40                                                                              49/51                                                                              61/39                                                                              61/39                                                                              60/40 48/52                                                                              61/39                                                                              60/40                                                                              61/39                     (molar ratio)                                                                 Molecular Weight                                                                         2200 1330 2500 2500 2200  1860 2500 2200 2500                      (number average)                                                              Initiator                                                                     Type       t-Bu.sup.(3)                                                                       Dicup.sup.(4)                                                                      Dicup                                                                              Dicup                                                                              Dicup t-Bu Dicup                                                                              t-Bu t-Bu                      Parts/100 Parts                                                                          5.4  20   16.6 10   5.4 + 5.4.sup.(5)                                                                   5.4  9.2  5.4  5                         Backbone Polymer                                                              Modified Polymer                                                              Allyl Glycidyl Ether                                                                     25   30   38   25   25 + 25.sup.(5)                                                                     25   10   25   20                        (Parts)(AGE)                                                                  Epoxy Groups                                                                             4.5  9.7  5.0  5.2  5.9   4.4  2.9  4.3  1.4                       (weight percent)                                                              Molecular Weight                                                                         2610 1310 2850 3040 2690  1990 3730 2190 3210                      (number average)                                                              Epoxy/Chain                                                                              2.8  3.0  3.3  3.7  3.7   2.1  2.5  2.2  1.0                       Brookfield Viscosity                                                                     34.5 --.sup.(6)                                                                         470  670  244   29.4 590  40.8 123                       (cps)/1000 at 25° C.                                                   __________________________________________________________________________     .sup.(1) Zr: (C.sub.5 H.sub.5)ZrCl.sub.2 catalyzed                            .sup.(2) V: VOCl.sub.3 catalyzed                                              .sup.(3) tBu: ditertbutyl peroxide                                            .sup.(4) Dicup: dicumyl peroxide                                              .sup.(5) Reaction run first on unfunctionalized EP using 25 phr AGE and       5.4 phr Dit-butyl peroxide. Epoxidized EP was then reacted again with 25      phr AGE and 5.4 phr Dit-butylperoxide.                                        .sup.(6) "--": Indicates not measured                                    

Formulations of the above graft polymers were prepared in accordancewith one of the following seven recipes:

    ______________________________________                                        Recipe   (a)     (b)    (c)   (d)  (e)   (f)  (g)                             ______________________________________                                        Graft    100     100    100   100  100   100  100                             Polymer                                                                       C.sub.12 -C.sub.14                                                                      23      50     65    30   50    50   --                             alkyl                                                                         glycidyl ether                                                                Nonylphenol                                                                             10      50     50    50   50    50   --                             Triethylene-                                                                            7.8     7.6    8.1   6.0  7.2   6.3  3.4                            tetramine                                                                     ______________________________________                                    

Twenty-five grams of each of the above encapsulation compositions werepoured into an aluminum dish heated to 53° C. (127° F.). A glass rod wasfrequently dipped into the encapsulation composition mixture until thepolymer had a tendency to snap back. The time from mixing to snap-backcondition is considered the gel time (in minutes). The recipes of eachcomposition prepared and the physical properties of the curedcompositions are listed in Table III (below).

                                      TABLE II                                    __________________________________________________________________________    Epoxy-Grafted Ethylene/Propylene Copolymers                                   EXAMPLE   1   2   3   4   5   6   7   8   9                                   __________________________________________________________________________    Recipe    (d) (a) (e) (b) (c) (d) (f) (d) (g)                                 Gel Time @                                                                              25  <20 7   13  10  19  21  28  73                                  53° C.(min)                                                            Shore A   6   --  13   9  18   6  1   7   6                                   Percent Elongation                                                                      50-100                                                                            <50 50-100                                                                            50  40  50-100                                                                            150 50-75                                                                             100                                 at Break                                                                      Days Cure 5   0.7 0.7  5   5  10  0.7 0.7 3                                   @ Temp.   26° C.                                                                     53° C.                                                                     53° C.                                                                     24° C.                                                                     24° C.                                                                     24° C.                                                                     53° C.                                                                     53° C.                                                                     53° C.                       __________________________________________________________________________     The above results indicate the short gel time and low temperature     curability of the encapsulation compositions of this invention, thus     demonstrating their utility for the on-site encapsulation of     telecommunication cable segments.

EXAMPLES 10-11

Following a procedure essentially identical to that described in Example1, several ethylene/propylene/dicyclopentadiene terpolymers, eachcomprising 5 molar percent dicyclopentadiene, were grafted with allylglycidyl ether. Formulations of these polymers were perpared (asdescribed in Example 1 above) and analyses of the cured compositionsperformed. The graft polymers produced, along with the results of suchanalyses, are summarized in Table III.

                  TABLE III                                                       ______________________________________                                        EPOXY-GRAFTED EPDM                                                            Example             10       11                                               ______________________________________                                        Backbone Polymer                                                              Catalyst            VOCl.sub.3                                                                             VOCl.sub.3                                       Ethylene/Propylene molar ratio                                                                    57/43    57/43                                            Molecular weight    2400     2400                                             (number average)                                                              Initiator                                                                     Initiator           benzoyl- dicumyl                                                              peroxide peroxide                                         Parts/100 Parts Backbone Polymer                                                                  4        10                                               Graft Polymer                                                                 Allyl glycidyl ether (parts)                                                                      25       25                                               Weight percent epoxy                                                                              0.8      3.4                                              Molecular weight    2290     1970                                             (number average)                                                              Epoxy/chain         0.4      2.3                                              Brookfield Viscosity @ 24°                                                                 265      720                                              (centipoise/1000)                                                             Cured Properties                                                              Recipe              (g)      (f)                                              Gel time @ 51° C. (min.)                                                                   275      10                                               Shore A             1        7                                                Percent Elongation at Break                                                                       200      50-100                                           Days Cure @ Temp.   3/53° C.                                                                        0.7/53° C.                                ______________________________________                                    

The above results indicate the usefulness of the expoxy-grafted EPDMpolymers of this invention in telecommunication cable encapsulationcompositions.

EXAMPLES 12 AND 13

Certain homopolymers within the scope of this invention were epoxidized,following generally the procedure of Example 1. Analyses and results aresummarized in Table IV.

                  TABLE IV                                                        ______________________________________                                        EPOXY-GRAFTED POLYALPHAOLEFINS                                                Example       12           13                                                 ______________________________________                                        Polymer       Polypropylene.sup.(1)                                                                      Polydecene-1.sup.(2)                               Molecular weight                                                                            ca. 800      2000                                               (number average)                                                              Graft Polymer                                                                 Weight percent epoxy                                                                        5.9          3.7                                                Molecular weight                                                                            830          --.sup.(3)                                         (number average)                                                              Epoxy/chain   1.1          ca. 1.7                                            Brookfield Viscosity                                                                        33,300       --.sup.(3)                                         @ 25° C.                                                               Recipe        (a)          (b)                                                Gel time @ 53° C., min.                                                              13           (4)                                                ______________________________________                                         Remarks:                                                                      .sup.(1) Amorphous atactic polypropylene; prepared with (C.sub.2              H.sub.5).sub.2 ZrCl.sub.2 catalyst/methaluminoxane cocatalyst.                .sup.(2) Polydecene; bulk viscosity at 100° C. = 100 cst.              .sup.(3) "--" indicates not measured                                          .sup.(4) Cured within 24 hours at room temperature.   Good results are        achieved when the above polymers are employed in encapsulation     compositions for telecommunication cable segments.

EXAMPLES 14-17

Several ethylene/propylene copolymers were modified by grafting ontothem allyl glycidyl ether by a process essentially identical to thatdescribed in Example 1. Two of these copolymers (Examples 14 and 15)were prepared using a VOCl₃ -based Ziegler-Natta catalyst system and two(Examples 16 and 17) were made employing a zirconiumcatalyst/methaluminoxane cocatalyst system. The resultant polymers wereanalyzed, which analyses are summarized in Table V below. The backbonepolymers of Examples 14 and 15 do not exhibit vinylidene-typeunsaturation whereas analysis reveals that a major percentage of thebackbone polymer chains of Examples 16 and 17 possess vinylideneunsaturation.

                  TABLE V                                                         ______________________________________                                        Example      14       15       16     17                                      ______________________________________                                        VOCl.sub.3 -catalyzed                                                                      yes      yes      --     --                                      Zr-catalyzed --       --       yes    yes                                     Molecular weight,                                                                          2500     2500     2200   2500                                    initial                                                                       Molecular weight,                                                                          2340     2760     2460   2820                                    after grafting                                                                No. epoxy groups/                                                                          2.2      2.4      2.1    3.0                                     Chain                                                                         Brookfield   178,000  126,000  33,000 112,000                                 viscosity (25° C.)*                                                    ______________________________________                                         *Determined employing Brookfield [trademark] type HBT viscometer with         microcell; Spindle #21.                                                  

The above data clearly indicate the lower bulk viscosities observed forepoxy-grafted ethylene/propylene copolymers having vinylideneunsaturation relative to similar grafted copolymers produced fromcopolymers not having vinylidene-type unsaturation.

EXAMPLES 18 AND 19

Additional low molecular weight ethylene/propylene copolymers wereprepared employing (in Example 18) a catalyst composition comprising (C₅H₅)₂ ZrCl₂ and (in Example 19) a catalyst composition comprising VOCl₃.The zirconium-catalyzed copolymers exhibited vinylidene unsaturationwhereas the vanadium-catalyzed copolymers did not exhibitvinylidene-type unsaturation. These copolymers were grafted with allylglycidyl ether by reacting such copolymers and ethers with dicumylperoxide. The physical properties of the graft copolymers are shown inTable VI.

These graft copolymers were formulated (as described in Table VI) intoencapsulation compositions. The initial Brookfield viscosities of suchcompositions and the gel times (i.e., the minutes until a viscosity of10⁵ centipoise was measured) were determined. In addition, the adhesionof said encapsulation compositions to a length of polyethylene insulatedcopper wire coated with a hydrocarbon grease type cable filling compoundwas measured by inserting a length of said wire into a 5 inch test tube;pouring in the encapsulation composition to be tested until it filled4.5 inches of such test tube; allowing the encapsulation composition tocure; and measuring the force required (in pounds) to withdraw the 4.5inch length of wire. The results of said testing are summarized in TableVI.

                  TABLE VI                                                        ______________________________________                                        Example             18         19                                             ______________________________________                                        Backbone Polymer                                                              Catalyst            (C.sub.5 H.sub.5).sub.5 ZrCl.sub.2                                                       VOCl.sub.3                                     Molecular Weight (number average)                                                                  2,500      2,500                                         Graft Copolymer                                                               Molecular Weight (number average)                                                                  2,770      3,020                                         Weight Percent Epoxy Groups                                                                           4.7        4.8                                        Brookfield Viscosity                                                                              138,000    350,000                                        (at 25° C.)                                                            Formulation Components.sup.(1)                                                EPIREZ 5018 (™).sup.(2)                                                                           65         65                                          Nonylphenol            50         50                                          Triethylene tetramine                                                                                 8          8                                          Formulation                                                                   Initial Brookfield Viscosity                                                                        1640       3600                                         (at 25° C.)                                                            Gel Time (min.)        371        65                                          Adhesion to Wire        4.8        2.9                                        ______________________________________                                         .sup.(1) In parts by weight per hundred parts graft polymer                   .sup.(2) monoglycidyl ether of C.sub.12 -C.sub.14 aliphatic alcohols          available from Celanese.                                                 

The above data further indicate the utility of the compositions of thisinvention in telecommunication cable encapsulation compositions.

EXAMPLE 20 AND COMPARATIVE EXPERIMENT A

An ethylene/propylene copolymer (Example 20) produced employing a (C₅H₅)₂ ZrCl₂ /methaluminoxane catalyst system, was grafted with allylglycidyl ether employing di-t-butyl peroxide as a free radicalinitiator. The graft polymers so produced comprised 4.5 weight percentepoxy groups, possessed a number average molecular weight of 1960, hadan average epoxy-functionality of 2.1 groups/chain, and possessed aBrookfield viscosity of 31,100 centipoise at 25° C.

The graft polymers so produced were formulated into an encapsulationcomposition employing recipe (d) described above. The composition soformed was tested for its moisture resistance, compatibility with cablefiller and adhesion to conductor wire.

The moisture resistance of the cured composition was determined byboiling a sample of the cured composition in water for one week, andnoting the percent change in hardness.

The compatibility of the encapsulant was measured employing thefollowing two tests: (A) Cured Absorption--a cured sample of theencapsulant (measuring 1 inch×1 inch×0.25 inch) was placed on top ofFlexgel™, a hydrocarbon grease-type cable filler, and aged for 7 days at60° C. The sample was weighted before and after aging and the precentweight change measured; (B) Curing Absorption: 15 grams of freshly mixedencapsulant poured on top of Flexgel™ cable filler and cured for 1 weekat room temperature. At the end of the test, the encapsulant was peeledoff the cable filler interface. The appearance of the interface and thepercent weight change of the encapsulation composition was determined.

The adhesion of the encapsulation composition to conductor wire wasdetermined as follows: conductor wire coated with Flexgel™, ahydrocarbon grease-type cable filler, was placed in a 5-inch test tubefilled to the 4.5 inch level with encapsulant. The sample was cured 4days at room temperature. After conditioning 1 hour at 60° C., the forcerequired to pull out the wire was recorded. The results of such testingare summarized in Table VII.

As a comparison (Comparative Experiment A), an identical series of testswere performed employing a urethane based encapsulant, known as DEncapsulant. D Encapsulant is currently used for fillingtelecommunication cable segments. The results of such testing are alsosummarized in Table VII.

                  TABLE IV                                                        ______________________________________                                        URETHANE VS EPOXIDIZED ETHYLENE/                                              PROPYLENE ENCAPSULANTS                                                        Example of                                                                    Comparative Experiment                                                                           A          20                                              ______________________________________                                        Backbone Polymer   Polyurethane                                                                             Ethylene/                                                                     Propylene                                                                     Copolymer                                       Moisture Resistance -                                                         Percent Change Hardness                                                                          -20        0                                               After One Week/Boiling Water                                                  Compatibility With Cable Filler                                               60° C./7 day Absorption - Cured                                                           -5.5       +21.6                                           Percent Weight Change                                                         Curing Absorption - 7-day                                                                        -2.5       +3.1                                            Room Temperature                                                              Percent Weight Change                                                         Appearance of Interface                                                                          Oily       Dry                                             Adhesion to Conductor Wire                                                    60° C. Wire Pull-out (lb./4.5"                                                            0.8        3.1                                             Wire Length)                                                                  ______________________________________                                    

The above data indicates the superiority of the compositions of thisinvention as splice encapsulants relative to the urethane basedencapsulation composition.

EXAMPLES 21-23 AND COMPARATIVE EXPERIMENTS B-E

In order to show the amorphousness of the polymers employed as backbonesin the graft polymer of the compositions of this invention relative tothe crystallinity of low molecular weight polyethylene waxes, themelting transition spectra of several samples of low molecular weightpolyethylene wax and of low molecular weight dicyclopentadienylzirconium dichloride/methaluminoxane catalyzed ethylene/propylenecopolymers ("EP") were evaluated employing a Perkin Elmer DifferentialScanning Calorimeter Model 2C. The purge gas employed was Helium, thesample size was 10-20 miligrams, and the scan was conducted at a rate of20 degrees/minute. The results of such testing are summarized in TableVIII below. It is to be noted that these curves would not be materiallyaltered by the grafting of epoxy-functionalized compounds to the extentcontemplated by the present invention.

                  TABLE VIII                                                      ______________________________________                                        Differential Scanning Calorimetry Comparison                                  Example          Weight         Differential                                  Com-             Per-           Scanning Calorimetry                          parative         cent    Molecu-                                                                              Peak (°C.)                             Experi-          Ethyl-  lar               Maxi-                              ment   Polymer   ene     Weight From  To   mum                                ______________________________________                                        B      Poly-     100      500   32    102  87                                        ethylene*                                                              C      Poly-     100     1000   67    127  117                                       ethylene*                                                              D      Poly-     100      900   34    102  60                                        ethylene**                                                             E      Poly-     100     1800   27    117  98                                        ethylene***                                                            21     EP         55     1470   -58    27  -30                                22     EP         59     7100   -34    35  -3                                 23     EP         40     5700   -52    37  -20                                ______________________________________                                         *Polywax 500 and 1000, available from Petrolight                              **Epolyn N14P, available from Eastman Chemical Products, Inc.                 ***Available from Boler Petroleum Co.                                    

The above-identified data clearly indicate that the polymers employed inthe composition of this invention are amorphous at room temperature whencompared with prior art polymers produced by the grafting of lowmolecular weight polyethylene waxes.

What is claimed is:
 1. A method of encapsulating a telecommunicationcable segment comprising the steps:(A) placing a telecommunication cablesegment within a closure; (B) forming an encapsulation composition bymixing:(1) a liquid graft polymer having a Brookfield viscosity of lessthan about 1,000,000 centipoise at 25° C., said graft polymer eitherpossessing no melting transition peak or a melting transition peakhaving a maximum value below 25° C. as measured by Differential ScanningCalorimetry; said graft polymer being comprised of: a polymeric backboneselected from the group consisting of polyalphaolefin,ethylene/alphaolefin copolymer, ethylene/alphaolefin/nonconjugatedpolyene terpolymer, polyisoprene, polybutadiene, and aalphaolefin/polyene copolymers; said polymeric backbone having graftedthereto a sufficient amount of at least one compound selected from theformulae: ##STR6## wherein R" is a C₂ -C₁₆ hydrocarbon radicalcontaining an ethylenically unsaturated bond or a C₃ -C₁₂ radicalcontaining one or more carbonyl groups and an ethylenically unsaturateddouble bond; andR' is hydrogen or C₁ -C₄ alkyl; such that said graftpolymer is rendered crosslinkable; said graft polymer having a numberaverage molecular weight of between about 500 and about 20,000; with (2)a sufficient amount of a suitable curative to cure the composition; (C)pouring a sufficient amount of said encapsulation composition into theclosure such that the portion of said cable segment to be embedded iscovered with said encapsulation composition; and (D) subjecting saidencapsulation composition to conditions sufficient to cure thecomposition.
 2. The method of claim 1 wherein said graft polymer has apolymeric backbone selected from the group consisting ofethylene/alphaolefin copolymer, polyalphaolefin andethylene/alphaolefine/nonconjugated polyene terpolymer.
 3. The method ofclaim 2 wherein said graft polymer has a polymeric backbone selectedfrom the group consisting of ethylene/propylene copolymer andethylene/propylene/nonconjugated diene terpolymer.
 4. The method ofclaim 3 wherein R" is a C₂ -C₁₂ hydrocarbon radical containing anethylenically unsaturated bond or is an acrylate or a methacrylateradical.
 5. The method of claim 2 wherein said polymeric backbone hasgrafted thereto allyl glycidyl ether.
 6. The method of claim 2 whereinsaid graft copolymer has a number average molecular weight of betweenabout 1,000 and about 4,500.
 7. The method of claim 1 wherein said graftpolymer has a number average molecular weight of between about 750 andabout 10,000.
 8. The method of claim 1 wherein said graft polymer has aBrookfield viscosity of less than about 500,000 centipoise at 25° C. 9.The method of claim 1 wherein the curing conditions in step (D) compriseambient pressure and temperature.